This invention pertains to caliper type disc brakes for wheeled vehicles, more particularly brakes of a size and style as used on heavier passenger cars, as well as trucks and other commercial vehicles of all weight categories, where the added cost of rotor ventilation is justified for cooling purposes.
Typically disc brake rotors for these applications have been made from iron castings which, through the use of foundry cores, have a plurality of usually tapered, radial air passages between the friction surfaces which act as a centrifugal fan when the rotor turns drawing air from around the axle on the side opposite the wheel and discharging this air in a radial direction from around the circumference of the rotor.
Additionally, some high performance solid disc brake rotors such as used on motorcycles and light four wheel vehicles achieve a reduction in the build-up of wear debris on the caliper friction pads with holes in the rotor surfaces or in some cases just dimples in the friction surfacesxe2x80x94neither of which actually pump cooling air.
The invention is directed to a ventilated brake rotor, including a hub mounting face, a rotor ring having two faces, and a hub wall connecting the hub mounting face to the rotor ring. The rotor ring has alternately faced passages disposed at an angle less than 90 degrees to the face of the rotor ring. Each passage passes through both the first and second face of the rotor ring.
Preferably, the passage outlet openings are radially farther from the rotor axis than the inlet openings, hence these passages will act like a fan due to centrifugal force to move air through the rotor mass for cooling when the ventilated brake rotor is rotated. A variation of the instant design would be one where the passages alternate directions such that half the inlets and half the outlets occur on each rotor surface.
Purposes and advantages of the novel design disclosed herein, in no particular order, are as follows:
1. Greater heat transfer from the rotor to the atmosphere due to the greater cooling air flow that will result from the larger less restrictive passages.
2. More uniform rotor cooling since both friction surfaces are benefited equally as a result of half the cooling air being drawn from the traditionally dead space between the rotor and the wheel. While with prior art rotors, the friction surface facing the wheel will run hotter than the friction surface facing away from the wheel, since the surface away for the wheel is exposed to the slip stream in the open atmosphere.
3. Less heat transfer to the tires from the brake rotor due to more uniform rotor cooling, again for the same reason as in 2.
4. Better cooling of the caliper friction pads as a result of their being swept and fanned as the openings pass them by.
5. Less heat transfer to the caliper friction pads from the brake rotor due to better rotor cooling, again for the same reason as in 2.
6. Improved braking due to the reduction in the build-up of wear debris on the caliper friction pads resulting from the passages sweeping and fanning the caliper friction pads per 4 above.
7. Reduced manufacturing cost due to the simplified foundry coring and core removal.